Tests and treatment for chronic myelomonocytic leukaemia (CMML)

Many people are diagnosed with CMML because doctors find abnormal monocytes during a blood test for something else. Your doctor may then arrange a number of tests for you, including:

  • blood tests to look at how many blood cells you have and whether they are normal
  • a bone marrow test

Your doctor may also do tests on the bone marrow to look for changes in the chromosomes Open a glossary itemof the CMML cells. Chromosomes contain the genetic material inside cells. These tests are called cytogenetics (pronounced sigh-toe gen-et-ics).

Doctors are learning more about CMML all the time. You might have other tests done on the bone marrow to look for other gene changes. You might hear this called myeloid next generation sequencing (NGS).

Treatment for CMML

The type of treatment you need depends on:

  • the type of CMML you have
  • whether you have symptoms
  • your age and whether you have any other medical conditions

You and your specialist discuss your treatment plan before you start.

Watchful waiting

If you have no or few symptoms you might not need treatment at first. Instead you will have regular check ups including blood tests. This is called watchful waiting.

Supportive treatment

The aim of supportive treatment is to:

  • improve your symptoms
  • improve your quality of life
  • delay a possible transformation of acute myeloid leukaemia

Donor (allogeneic) stem cell or bone marrow transplant

The only way to cure CMML is to have a stem cell transplant from a matched donor. This is usually either a matched sibling or a matched unrelated donor.

This is an intensive treatment and it has many risks. This is why it’s unfortunately not suitable for everyone.

Supportive treatment

Most people need supportive treatment at some point. The treatment you need depends on the type of symptoms you have. You might need a combination of treatments.

Blood and platelet transfusions

You might have blood transfusions if your red blood cells are low.

If your platelets are low you might require platelet transfusions, especially if you are experiencing any symptoms of bleeding.

Having a lot of blood transfusions can cause a build up of iron in your body. Red blood cells contain iron and your body stores this. But too much iron in your body can damage your heart and liver. To stop this, you might need to take medicines to get rid of the extra iron.

Growth factors

Growth factors are drugs that encourage your bone marrow to make more blood cells. We know from research that this can reduce the number of blood transfusions that people need.

Erythropoetin is a growth factor that increases the number of red blood cells. So, you might have this if your red blood cell level is low. 

G-CSF is a growth factor that increases the number of white blood cells. So, you may have this if your white blood cell levels are low.

You have both of these drugs as injections just under the skin (subcutaneously). You might have some training so you're able to do these injections yourself.


You might also need to take antibiotics to treat infection, and sometimes to prevent infection.

Chemotherapy for CMML

Chemotherapy uses cell killing (cytotoxic) drugs to destroy the abnormal cells.

The drugs work by disrupting the growth of cells and stopping them from dividing. You can have chemotherapy as a tablet, an injection just under your skin, or as an injection into a vein. You might have just one drug or a combination of drugs.

The type of chemotherapy you have depends on your type of CMML and your general health. If you have just been diagnosed your first chemotherapy might be azacitidine, hydroxycarbamide or low dose cytarabine.

Some people have more intensive chemotherapy.


Azacitidine is a type of drug called a hypomethylating agent. It works by switching off a protein called DNA methyltransferase.

This switches on genes that stop the cancer cells growing and dividing. This reduces the number of abnormal blood cells and helps to control cell growth.

You usually have azacitidine as an injection just under your skin (subcutaneously) given by a doctor or nurse. You usually have this at the hospital. You have treatment each day for a week and then 3 weeks with no treatment. This makes up a treatment cycle. 

Hydroxycarbamide (hydroxyurea)

You might have hydroxycarbamide to help control a high white cell count. Hydroxycarbamide is one of a group of chemotherapy drugs known as anti metabolites. These drugs stop cells making and repairing DNA. Cancer cells need to make and repair DNA in order to grow and multiply.

You usually take this as an oral capsule every day.

Low dose cytarabine

You might have low dose cytarabine if you can not have hydroxycarbamide.

Cytarabine kills cancer cells by stopping them from making and repairing DNA that they need to grow and multiply.

You usually have it as an injection under the skin (subcutaneous) twice a day for 10 days. You, or a family member, might be able to get training so you’re able to do this yourself. Or your local district nurses might be able to give your injections.

You have low dose cytarabine in courses (cycles) of treatment.

Intensive treatment

You might have intensive chemotherapy with the aim to get the CMML under control before a stem cell transplant.

This is similar to the chemotherapy some people have for AML.

You might have:

  • fludarabine, cytarabine and idarubicin (FLAG - Ida)
  • cytarabine and daunorubicin (DA)

Donor stem cell transplant

Donor stem cell transplants are usually only suitable for people who:

  • are younger
  • are in reasonably good health, apart from your CMML
  • have a suitable donor (sibling or unrelated)
  • have CMML that is more difficult to treat

This is because it’s an intensive treatment and there are risks. There are several stages to a donor stem cell transplant.

Stages of a donor stem cell transplant

You have a stem cell transplant after chemotherapy treatment. You might have targeted drugs with the chemotherapy. You may also have radiotherapy to your whole body. This is called total body irradiation or TBI.

The radiotherapy, chemotherapy and targeted drugs have a good chance of killing the CMML cells. But it also kills the stem cells in your bone marrow. 

Some people who have a donor transplant might have a mini transplant. This is also called a reduced intensity conditioning (RIC) transplant. 

You have lower doses of chemotherapy than in a traditional stem cell transplant. You might have this treatment if you are older (usually over 50 years), or not fit or well enough for a traditional transplant.

After this treatment you have stem cells from a donor to replace your own bone marrow cells. You have these through a drip into your bloodstream.

To be able to have intensive treatment you need a stem cell donor. The donor is someone whose stem cells match yours. The most suitable donor is usually a close relative such as a brother or sister. If you don't have a suitable family donor your doctor might look for an unrelated donor for you.

It takes from a few days to a few weeks for the donor stem cells to start making new blood cells. During this time, you will need blood and platelet transfusions. You are also at a high risk of developing infections, so you have antibiotics and anti viral drugs to try to prevent this from happening.

Graft versus host disease (GvHD)

Graft versus host disease (GvHD) can be a serious possible complication of a stem cell or bone marrow transplant from another person. GvHD means the graft reacts against the host. The graft is the marrow or stem cells from the donor. The host is the person having the transplant. You have treatment to prevent GvHD. The aim is to try to lower the risk of serious GvHD as far as possible.


Researchers around the world are looking at better ways to treat myeloproliferative or myelodysplastic disorders and manage treatment side effects.These clinical trials sometimes include people who have CMML.

A study is setting up a record or ‘registry’ of information about a large number of people across Europe with blood cancers including CMML. If you take part, the team will collect information about your medical history, test results and treatments. Doctors also want to find out as much as possible about the many different types of myelodysplastic or myeloproliferative disorders and how best to treat them.

Cancer Research UK Clinical Trials Database

You can find a clinical trial looking at CMML on our clinical trials database. Click on the ‘recruiting’, ‘closed’ and ‘results’ tabs to make sure you see all the trials.

You need to talk to your specialist if there are any trials that you think you might be able to take part in.

Coping with CMML

Coping with a rare condition can be difficult, both practically and emotionally. Being well informed about your condition and its treatment can help you to make decisions and cope with what happens.

Last reviewed: 
20 Aug 2020
Next review due: 
20 Aug 2023
  • Diagnosis and Treatment of Chronic Myelomonocytic Leukemias in Adults

    Recommendations From the European Hematology Association and the European LeukemiaNet

    R Itzykson and others

    HemaSphere, 2018. Volume 2, Issue 6

  • Cancer Research UK Clinical Trials Database

    Accessed August 2020

  • ClinicalTrials.gov website

    Accessed August 2020

  • Azacitidine for the treatment of myelodysplastic syndromes, chronic myelomonocytic leukaemia and acute myeloid leukaemia

    National Institute for Health and Care Excellence (NICE), 2011

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